Device for distributing hot-melt adhesive

ABSTRACT

This invention relates to a device for applying discrete amounts of hot-melt adhesive on surfaces of materials such as paper, cardboard, and the like. More particularly, the invention relates to a device enabling a nozzle to be utilized for applying small or large amounts of hot-melt adhesive on surfaces. The amounts may be deposited in the form of spots on in the form of continuous layers.

United States Patent 191 Spencer 401/1 Busoni Dec. 10, 1974 DEVICEFOR'DISTRIBUTING HOT-MELT 2,118,415 5/1938 Pesark 401/1 ADHESIVE3,143,756 8/1964 Sisko 401/188 3,195,170 7/1965 Howard 401/188 [76]Inventor: Rodolfo Busoni, Via Lazzaretto 3,443,059 5 19 9 Vecchio 7,34123 Trieste, Italy 3,662,927 5/1972 Cocks 40l/l X [22] Flled. Oct.1972 Primary Examiner-Lawrence Charles PP 298,615 Attorney, Agent, orFirm--Steinberg & Blake [30] Foreign Application Priority Data [57]ABSTRACT 0m. 22, 1971 Italy 30200 71 This invention relates to a devicefor pp y discfete amounts of hot-melt adhesive on surfaces of materials52 US. (:1 401/1, 222/146 HE such as p p cardboard, and the like- More P51 Int. Cl A46b 11/08 larly, the invention relates to a device enabling8 [58] Field of Search 401 /1, 2; 222/146 HE 119 to be utilized for p ysmall or large amounts of hot-melt adhesive on surfaces. The amounts maybe 5 Referemes Cited deposited in the form of spots on in the form ofcon- UNITED STATES PATENTS Imus layers- 1 32g 7 9 920 10 Claims, 5Drawing Figures PATENTEL UEBHJIQH 3,853,411 0 SNEEI 3 OF 2 DEVICE FORDISTRIBUTING HOT-MELT ADHESIVE In the particular art to which thepresent invention relates there are known devices for applying on thesurfaces of materials such as paper lines or spots of hotmelt adhesive.The term spot is intended to refer to application of adhesive to a smalldefinitive area having a substantially circular configuration. In orderto apply such spots, there are devices which includea premelting chamberand a melting chamber, these chambers being separated from each other bya filter. The hotmelt adhesive is melted by means of electrical heatingresistances, and then the melted adhesive passes through the filter inorder to reach the melting chamber where the temperature of the meltedadhesive is maintained at the required value through the use of athermostatically controlled heating resistance. A pneumatic piston pumpprovides by way of its reciprocating motion for the supply of suitableamounts of adhesive, such amounts being supplied to a head whichincludes a fixed dispensing nozzle controlled by a needle valve. Areturn line or duct which leads to the melting chamber is connected tothe head. As a result, two tubes, namely a supply tube and a returntube, are connected to the latter head. During use of such a structure,the opening of the needle valve enables desired amounts of adhesive tobe dispensed. When this valve is closed, and inasmuch as the pneumaticpump continues to operate, the adhesive is first delivered to the headand then returns to the melting chamber.

A first disadvantage of a circuit of this latter type resides in thefact that it must include return and supply pipes. In addition there isthe disadvantage that inasmuch as the nozzle is stationary it isnecessary, in order to provide adhesive spots in an accurate manner,that the nozzle be vertically directed with respect to a horizontalsurface with the jet issuing from the nozzle being directed downwardly.

It is therefore an object of the present invention .to provide a devicefor applying lines or spots of hot-melt adhesive on surfaces, whilebeing capable of utilizing for this purpose a jet which is directed'in adirection other than a vertically downward direction.

A still further object of the present invention'is to provide a devicewhich enables only a single duct to be used for connecting the nozzlewith the melting chamher.

A still further object of the present invention is to provide a devicewhich avoids the necessity of utilizing a source of compressed air inorder to supply the molten adhesive to the nozzle.

A device according to the present invention includes a premeltingchamber, a melting chamber, a pump, and a nozzle, and is characterizedin that the nozzle is movable and during dispensing of the adhesive isin substantial contact with the surface on which the adhesive isapplied.

According to a particular aspect of the present invention, the pump is agear pump driven by an electric motor through a reducer, and the outletof the pump is connected to the nozzle by way of an overpressure valveand a relief valve which, together with the pump, are located within themelting chamber. In this way any portion of the pump fluid whichdischarges from the pump without being dispensed by the nozzle willreturn back into the melting chamber through the relief valve,

so that in this way only a single duct is required to connect the nozzleto the pump.

According to a preferred embodiment of the invention a gear pumpincludes a gear mounted on a shaft driven by the motor, while a secondgear is supported in a floating manner within the chamber of the pump.

The invention will be better understood from the following detaileddescription of a preferred embodiment, illustrated by way of anon-limiting example in the accompanying drawings, in which:

FIG. 1 is a schematic partly vertical sectional view showing the deviceof the present invention, with the nozzle being operated by a solenoid;

FIG. 2 shows schematically a detail of a pressure control valve;

FIG.'3 illustrates the flow circuit of the device of the invention;

FIG. 4 is a vertical sectional view of details of the nozzle; and

FIG. 5 is a schematic illustration of a different embodiment of thenozzle as utilized in connection with a gun-type of device held by theoperator.

Referring to FIGS. 1-3, the device illustrated therein according to thepresent invention comprises a body or reservoir 1, preferably made ofaluminum. Against the exterior surface of the bottom 2 of the reservoirthere are electrical heating resistances 3 controlled by anunillustrated thermostat.

The interior of the reservoir 1 is divided into two portions by a wiremesh 4 which acts as a filter and which has incorporated therein apreheating resistance which is controlled by the thermostat. The space 5situated above the mesh 4 forms the premelting chamber in which solidadhesive may be melted. Upon melting the adhesive will filter throughthe mesh 4 while dropping down into the lower chamber 6 which issituated beneath the mesh 4 and which forms the chamber in which theadhesive is maintained in a molten condition. Within this lowerchamber-6 is a gear pump 7 having a delivery or outlet conduit 8 whichcommunicates with a relief valve 10. As may be seen from FIG. 3, aconduit 8A is connected in parallel with the pump 7 and carries anoverpressure valve 9. The gear pump 7 is driven by a variable speedelectric motor 11 through a toothedbelt reduction drive 12. 7

As may be seen from FIG. 2, the pressure regulator or relief valve 10 islocated in a conduit 13 branching from the delivery or outlet conduit 8of the pump. This conduit 13 is closed at its top open end by a ball 14which is loaded by and thus under the pressure of a spring 15 theconvolutions of which become gradually smaller in a downward direction,as viewed in FIG. 2. The other end of the spring 15 presses against apiston 16 which slides within a cylinder 17. A cam 18 presses againstthe top surface of the piston 16 and is carried by a rotary spindle 19supported within the casing of the pressure regulator. The spindle 19projects laterally to the exterior of the reservoir 1 and at itsprojecting end it carries a knob or handle 20. Thus the operator cangrasp the handle or knob 20 in order to change the angular position ofthe cam 18 and thus change the force with which the spring 15 acts onthe ball 14. The chamber 17, in which the ball 14 is accommodated, isconnected directly through the conduit 21 with the lower portion 6 ofthe reservoir 1.

The delivery conduit 8 is connected downstream of the pressure regulator10 through a conventional swivel joint 22 with a flexible hose 23 aroundwhich a thermostatically controlled heating wire resistance 24' iswound. The hose 23 terminates in the nozzle head 24.

As may be seen from FIGS. 1, 3, and 4, the head 24 includes a housingabove which an electromagnet 25 is mounted, this electromagnet 25 havinga movable core 26 (FIG. 4) pressing against the head 26A of a slidablymounted nozzle 27 urged toward the core 26 by a spring 28. This spring28 is situated within a tubular element 29 secured in a known way withinan aperture 30 formed in the head 24.

The nozzle 27 has a pair of opposed inclined surfaces 31 which convergedownwardly toward each other, as viewed in FIG. 4, with these surfaces31 joining at their lower ends a pair of opposed parallel surfaces 32which extend parallel to the axis of the nozzle 27. At these inclinedsurfaces 31 the nozzle 27 is formed with a transverse bore 33 whichcommunicates with an axial bore 34 formed in the nozzle 27 and openingat its lower end, as viewed in FIG. 4, into the interior of aninternally threaded outer nozzle member 34A, which is threaded onto theouter end of the nozzle 27 and which is provided with a small nozzleopening 35. The fluid jet will issue to the exterior through the opening35.

The tubular member 29 which supports the nozzle 27 is formed with a pairof apertures 36 respectively aligned with the zones 31, 32 of the nozzle27. A ball 37 is situated in each of these apertures, and the force of aspring 38 is transmitted to each ball 37 through a member 39 so that theballs 37 engage the inner circular edges of member 29 at the innersmaller ends of the apertures 36 thereof. These apertures 36 extendinwardly from an annular groove 41 formed around the exterior of themember 29, this groove 41 communicating with a conduit 40 as shown indotted lines in FIG. 4. It is to this conduit 40 that the hose 23 isconnected.

Assuming that an electrical pulse is applied to the electromagnet 25,the core 26 thereof will move downwardly, as viewed in FIG. 4, thusdisplacing the nozzle 27 downwardly in oppossition to the spring 28 withthe head 26A acting as an abutment against which the core 26 acts.Therefore, the inclined surfaces 31 will become situated between theballs 37 to displace the latter outwardly in opposition to the springs38, with the result that the fluid adhesive supplied by the pump 7 cannow flow from the annular groove 41 into and through the apertures 36 toreach the transverse bore 33 so as to flow from the latter along theaxial bore 34. In this way the adhesive will reach the nozzle outlet soas to flow from the latter into contact with the surface to which theadhesive is to be applied. During this stage of the operation the lowerend of the nozzle 27, or in other words the member 34A thereof, will beheld by the operator in engagement with the surface which is to receivethe adhesive so that in this way an adhesive spot or line can beapplied. When the energizing of the solenoid 25 is terminated, thespring 28 will expand to displace the inclined surfaces 31 away fromtheir position between the balls 37 so that the latter will again bepressed by the springs 38 through the members 39 into the positionswhere these balls 37 close the apertures 36, and thus the flow ofadhesive will be terminated. It

is apparent, therefore, that with this construction the distributinghead can be utilized in any position.

FIG. 5 illustrates an embodiment wherein the head is a gun-type ofcomponent capable of being held by the operator. In this case theconduit 23 is connected to a conduit 50 which extends through thegun-type of dispenser. As is shown at the right of FIG. 5, the conduit50 opens into an annular groove 51 formed at the exterior of a tubularelement 52 which is secured in the gun-type of dispenser in any suitableway. A nozzle 53, corresponding to nozzle 27, slides within this tubularelement 52. A ball valve 54, substantially similar to the ball valve 37,normally closes an aperture 55 formed in the tubular element 52 andserves to connect the annular chamber 51 with the bore 56 of the nozzle.This bore 56 of course extends to the exterior of the nozzle through asmall nozzle outlet as was the case with the embodiment of FIG. 4.

In connection with the nozzle of FIG. 5, the nozzle 53 is urged by aspring 57 toward a slidable push member or wire 58 which engages a head61 against which the spring 57 presses, this head 61 being fixed to theinner or upper end of the nozzle 53. The pusher 58 is encased within asheath 59, forming a Bowden cable, and, as shown at the lower part ofFIG. 5, when the trigger 60 is turned in a clockwise direction, asviewed in FIG. 5, the inner wire 58 of the Bowden cable'assembly will bepushed within its sheath so as to cause the nozzle 53 to be depressed inopposition to the force of the spring 57. In this way the moltenadhesive'will discharge from the nozzle as described above in connectionwith FIG. 4.

Thus it will be seen that with the invention there is a reservoir means1 defining the chamber 6 for the hotmelt adhesive as well as thepremelting chamber 5 separated from chamber 6 by the wire filter 4 whichincludes additional heating wires. The hot-melt adhesive is delivered tothe desired location by way of the nozzle means 24 which includes thehousing of FIG. 4 or FIG. 5 together with the combined nozzle and valveunit which is shifted in its entirety with respect to the housing inorder to open or close the flow of hot-melt adhesive to the outlet ofthe nozzle. In the case of FIGS. 3 and 4, the combined nozzle and valveunit is shifted in its entirety in an electrical manner by way of thesolenoid 25 while in FIG. 5 the combined nozzle and valve unit isshifted in its entirety as a result of manual operation of elements58-60. Thus in FIGS. 3 and 4 there is an electrical means for shiftingthe combined nozzle and valve unit from its closed to its open positionwhile I in FIG. 5 there is a manual means for shifting the combinednozzle and valve unit from its closed to its open position, with theunit being returned in each case to its closed position by way of aspring means. The nozzle means can be movedfabout as desired as a resultof the flexible hose 23 which forms part of a supply means for supplyingthe hot-melt adhesive from the reservoir means 1 to the nozzle means 24.This supply means includes not only the flexible hose 23 but also thepump means 7 which serves to urge the hot-melt adhesive continuouslytoward the nozzle means 24 so that whenever the combined nozzle andvalve unit is shifted to its open position there will be an immediatedischarge of hot-melt adhesive. In order to maintain this constantreadiness to supply hot-melt adhesive during operation of the device,the pump means is operatively connected on the one hand with theadjustable relief valve means 10 and on the other hand the suction anddelivery portions of the conduit 8 leading to and from the pump means 7are interconnected by the parallel-connected conduit 8A which includesthe over-pressure valve 9. Furthermore, it is to be noted that all ofthe supply means except the flexible hose 23 is situated within thechamber 6 of the reservoir means 1.

Although only two embodiments of the invention have been described,those skilled in the art can now readily devise many changes andmodifications, all of which are intended to be within the scope of theinvention.

According to a further feature of the invention, while one gear of thepump is carried by a shaft, the other gear thereof is mounted in afloating manner within the pump chamber.

What I claim is:

l. A device for distributing a hot-melt adhesive, comprising reservoirmeans defining an interior chamber for containing a supply of hot-meltadhesive, nozzle means for applying the hot-melt adhesive to a desiredlocation, and supply means communicating on the one hand with saidchamber and on the other hand with said nozzle means for continuouslyurging the hot-melt adhesive to flow from said reservoir means to saidnozzle means, said supply means including a flexible hose operativelyconnected with said nozzle means so that the latter may be freely movedwith respect to a surface to which the hot-melt adhesive is distributed,said nozzle means including a housing, a combined valve and nozzle unitshiftable with respect to said housing between a closed positionpreventing the adhesive from issuing from said nozzle means and an openposition opening said nozzle means to permit the adhesive to bedistributed by said nozzle means, spring means urging said unit to itsclosed position, and means operatively connected with said nozzle meansfor shifting said unit in opposition to said spring means from saidclosed to said open position thereof.

2. The combination of claim 1 and wherein a manually operable means isoperatively connected with said nozzle means for operating the latter.

3. The combination of claim 1 and wherein an electrical means isoperatively connected with said nozzle means for operating the latter.4. The combination of claim 1 and wherein said supply means includes apump for continuously urging the adhesive to flow from said chamber tosaid nozzle means and a pressure-relief valve means communicating withthe outlet of said pump and with said reservoir means for returningadhesive to said reservoir means when a given pressure at the outlet ofsaid pump is exceeded, said pump and said pressure-relief valve meansboth being situated in said interior chamber of said reservoir means atan elevation low enough to be immersed in a supply of hot-melt adhesive.

5. The combination of claim 4 and wherein an adjusting means operativelyconnected with said pressurerelief valve means for adjusting said givenpressure.

6. The combination of claim 1 and wherein said supply means includes apump in said interior chamber of said reservoir means for continuouslyurging the adhesive to flow from said reservoir means to said nozzlemeans, said pump having an inlet and an outlet and said supply meansincluding a conduit in said interior chamber of said reservoir meansconnected in parallel with said pump and communicating with said inletand outlet thereof, said conduit carrying an overpressure valve in saidinterior chamber of said reservoir means which acts for automaticallyreturning adhesive from said outlet to said inlet when a given pressureis exceeded, said pump, conduit, and overpressure valve being situatedat an elevation in said interior chamber low enough to be immersed in ahot-melt adhesive contained by said reservoir means.

7. The combination of claim 1 and wherein said chamber of said reservoirmeans is a main chamber thereof, said reservoir means including apremelting chamber and a filter situated between said premelting chamberand said main chamber, said filter being in the form of a wire meshincluding at least some wires which form heating elements.

8. The combination of claim 1 and wherein said supply means includes agear pump.

9. The cornbination'of claim 8 and wherein said gear pump includes adriven pump gear and a floating pump gear.

10. The combination of claim 1 and wherein said housing of said nozzlemeans includes an interior tubular guide, said combined valve andnozzlef unit being shiftable in said tubular guide and being in the formof an elongated body formed with an axial bore which at one end isprovided with a nozzle outlet, and said body being formed inwardly ofsaid nozzle outlet with a transverse bore communicating with said axialbore, said tubular guide being formed with an opening passingtherethrough at the region of said transverse bore and said openingcommunicating with the interior of said hose so that hot-melt adhesivecan flow through said opening into said transverse bore and from thelatter through said axial bore to said nozzle outlet, and aspring-pressed ball member situated in said opening of said tubularguide for closing saidopening to prevent the hot-melt adhesive fromreaching said transverse bore when said unit is in said closed positionthereof, said body having at the region of said transverse bore thereofan exterior camming surface which engages said spring-pressed ballmember to displace the latter to a position unblocking said opening whensaid unit is shifted to said open position for then providing flow ofthe hot-melt adhesive past said spring-pressed ball member through saidopening into said transverse bore to flow from the latter through saidaxial bore out through said nozzle outlet.

1. A device for distributing a hot-melt adhesive, comprising reservoirmeans defining an interior chamber for containing a supply of hot-meltadhesive, nozzle means for applying the hotmelt adhesive to a desiredlocation, and supply means communicating on the one hand with saidchamber and on the other hand with said nozzle means for continuouslyurging the hot-melt adhesive to flow from said reservoir means to saidnozzle means, said supply means including a flexible hose operativelyconnected with said nozzle means so that the latter may be freely moveDwith respect to a surface to which the hot-melt adhesive is distributed,said nozzle means including a housing, a combined valve and nozzle unitshiftable with respect to said housing between a closed positionpreventing the adhesive from issuing from said nozzle means and an openposition opening said nozzle means to permit the adhesive to bedistributed by said nozzle means, spring means urging said unit to itsclosed position, and means operatively connected with said nozzle meansfor shifting said unit in opposition to said spring means from saidclosed to said open position thereof.
 2. The combination of claim 1 andwherein a manually operable means is operatively connected with saidnozzle means for operating the latter.
 3. The combination of claim 1 andwherein an electrical means is operatively connected with said nozzlemeans for operating the latter.
 4. The combination of claim 1 andwherein said supply means includes a pump for continuously urging theadhesive to flow from said chamber to said nozzle means and apressure-relief valve means communicating with the outlet of said pumpand with said reservoir means for returning adhesive to said reservoirmeans when a given pressure at the outlet of said pump is exceeded, saidpump and said pressure-relief valve means both being situated in saidinterior chamber of said reservoir means at an elevation low enough tobe immersed in a supply of hot-melt adhesive.
 5. The combination ofclaim 4 and wherein an adjusting means operatively connected with saidpressure-relief valve means for adjusting said given pressure.
 6. Thecombination of claim 1 and wherein said supply means includes a pump insaid interior chamber of said reservoir means for continuously urgingthe adhesive to flow from said reservoir means to said nozzle means,said pump having an inlet and an outlet and said supply means includinga conduit in said interior chamber of said reservoir means connected inparallel with said pump and communicating with said inlet and outletthereof, said conduit carrying an overpressure valve in said interiorchamber of said reservoir means which acts for automatically returningadhesive from said outlet to said inlet when a given pressure isexceeded, said pump, conduit, and overpressure valve being situated atan elevation in said interior chamber low enough to be immersed in ahot-melt adhesive contained by said reservoir means.
 7. The combinationof claim 1 and wherein said chamber of said reservoir means is a mainchamber thereof, said reservoir means including a premelting chamber anda filter situated between said premelting chamber and said main chamber,said filter being in the form of a wire mesh including at least somewires which form heating elements.
 8. The combination of claim 1 andwherein said supply means includes a gear pump.
 9. The combination ofclaim 8 and wherein said gear pump includes a driven pump gear and afloating pump gear.
 10. The combination of claim 1 and wherein saidhousing of said nozzle means includes an interior tubular guide, saidcombined valve and nozzle unit being shiftable in said tubular guide andbeing in the form of an elongated body formed with an axial bore whichat one end is provided with a nozzle outlet, and said body being formedinwardly of said nozzle outlet with a transverse bore communicating withsaid axial bore, said tubular guide being formed with an opening passingtherethrough at the region of said transverse bore and said openingcommunicating with the interior of said hose so that hot-melt adhesivecan flow through said opening into said transverse bore and from thelatter through said axial bore to said nozzle outlet, and aspring-pressed ball member situated in said opening of said tubularguide for closing said opening to prevent the hot-melt adhesive fromreaching said transverse bore when said unit is in said closed positionthereof, said body having at the region of said transverse bore thereofan eXterior camming surface which engages said spring-pressed ballmember to displace the latter to a position unblocking said opening whensaid unit is shifted to said open position for then providing flow ofthe hot-melt adhesive past said spring-pressed ball member through saidopening into said transverse bore to flow from the latter through saidaxial bore out through said nozzle outlet.